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Finding the Fourth Proportional to 57, 85.40 and 39

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Solution

The fourth proportional to 57, 85.40 and 39 is: 58.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    57 : 85.40 = 39 : x
  2. Step 2: Convert to fraction form
    57/85.40 = 39/x
  3. Step 3: Cross multiply
    57x = 85.40 × 39
  4. Step 4: Simplify right side
    57x = 3,330.60
  5. Step 5: Solve for x
    x = 3,330.60/57
  6. Step 6: Final answer
    x = 58.43

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.